CA2044516A1 - Polymer compositions - Google Patents

Abstract

ABSTRACT POLYMER COMPOSITIONS Impact polymer compositions and peroxide-treated derivatives thereof demonstrate a good balance of low temperature properties and resistance to stress whitening when the homopolymer phase is at least predominantly homopolymeric propylene polymer and the rubber phase comprises, in descending order of proportion, ethylene, units of an .alpha.-olefin of at least 4 carbon atoms and propylene units.

Description

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This invention relates to propylene polymer compositions of good impact strength and toughness and also of improved rssistance to stress whitening.
Propylene polymer compositions have gained wid~
commercial acceptance in numerous commercial applications because of their relatively low cost and desira~le properties. In general, propylene polymers, particularly propylene homopolymer~t have the dieadvantage o~ being lO brittle with low impact resi~tance, particularly at low temperaturesO Numerous proposals have been made ~or modifying the properties of propylene homopolymer~ to improve impact strength and other low temperature properties. Many, if not most, o~ ~uch proposals have 15 involved the provision of a propylene/~-olefin copolymer portion in otherwise homopolymeric polypropylene. In US-A-3,514,501, ~here is described a process for the production of bloc~ copolymers wherein, for example, a prepolymer which is homopolymeric is produced and a block 20 which has at least one other ~-olefin is grown from the prepolymer in a second polymerization step. A second approach to providing improved impact ~trenyth comprises mixing a propylenP homopolymer with a propylene/ethylene copolymerO Most commercial products of high impact strength 25 result ~rom the production of a first polymer, usually a propylene homopolymer, and khe production o~ a multi-polymeric por$ion, usually termed a copolymeric portion in the presence of the initial polymer product mixture which still contains active polymerization sites. Whether the 30 resulting product is a block copolymer, a mixture of homopolymer and copolymer or of some other structure is not entirely claar. However, such products are well known in the art, are conventional and have achieved substantial commercial importance. They are o~ten referred to as 35 polypropylene impact copolymers, regardless of their precise structure, and are said to contain a homopolymer pha~e ` .' ` ' ' ' ''~ '` ` ' ' ' ' ' .

(o~ten homopolymeric polypropylene) and a rubber phase (the copolymer portion).
Such polypropylene impact copolymers, particularly those wherein ethylene is ~he other ~-ole~in of the 5 copolymer portion, do exhibit improved low tempera~ure impact str~ngth and other improved low temperature properties as well as many of the desirable properties of the homopolymer such as sti~fness. However, the impact copolymers have low resistance to stress whitening in 10 situations such as rapid impacting sr the bending of fabricated parts and also have poor to moderate toughness.
In the cas~ of impact copolymers having a high ethylene content in the copolymer phase, brittle failure is often observed upon impact. These high ethylene content polymers 15 do, however, show better re~i~tance to stress whitening.
The difficulty of obtaining a good balance of properties in a polypropylene composition has been addressed on numerous occasions, In EP A-208,330 there are disclosed compositions said to have improved resistance to stress 20 whitening which comprise homopolymeric polypropyl~ne or peroxide-degraded polypropylene having a grafted ethylene/propylene copolymer portion and, as an additional component, an ester derived from a C12-C20 monocarboxylic acid and a polyhydric alcohol. In JP-A-8~020522/04 ~here is 25 described a mixture of polypropylene of specified melt flow and an ethylene/~-olefin copolymer wherein the molecular weight of the polypropylene has been substantially reduced by treatment with peroxide. US-A-3,562,790 proposes obtaining better properties through the provision of a 30 ternary blend of homopolymers or copolymers and an amorphous aopolymer or terpolymer of ethylane, propylene and optionally an unsaturated hydrocarbon of at least one double bond.
In US-A-4,734,459, there are disclosed 35 polypropylene compositions comprising a homopolymer portion and a copolymer portion which comprises crystalline ~ .
.. . - . . . .
- , , . ~ ' . .

- 3 - ~3~
polyethylene and an amorphous ethylene/1-butene copolymer.
Care is taken to avoid the presence of propylene in the copolymer portion although provision is made for the presence in the gas phase of a small amount of propylene, 5 e.g. less than 5% by mole on the basis of monomers present.
Although these compositions do show some imprsvement in low temperature properties, the crystallinity in the rubber phase would be relatively high ~or compositions having the higher ethylene contents (in the rubber phase) needed ~or 10 better stress whitening resistance, and the compositions would be expected to be overly brittle. It would be of advantage to provide improved polypropylene compositions having an improved balance of properties including better low temperature properties such as strength and also yood 15 resistance to stress whitening.
The present invention provides an impact polymer composition comprising a) a homopolymer phase of at least predominately homopolymeric propylene polymer and b) a rubber phase containing, in descending order of proportion, ethylene units, units sf an ~-olefin of at least 4 carbon atoms and propylene units.
The compositions of the invention exhibit an improved balance of properties. These compositions, 25 suitably produced by gas phase processes in a two-stage reaction, are characterized by a homopolymer phase and a copolymer phase o~ defined proportions. The homopolymer phase is at least predominantly homopolymeric propylene polymer with an optional inclusion of a minor proportion of 30 ethylene units. The copolymer or rubber phase of the compositions of the invention contains primarily ethylene units but also incorporates units of propylene and of an ~-olefin of at least 4 carbon atoms.
The compositions of the invention can be produced 35 in the gas phase in the presence of a high activity, stereoregular olefin polymerization catalyst by methods ~. ' ~ . .. .

.

which are broadly conventional. ~he catalystæ are also broadly known, being employed in the polymerization of ~-olefins of three or more carbon atoms to pxoduce stereoregular polyol~fin product~. In terms conventionally 5 employed to describe such catalysts, th2 high activity stereoregular catalysts contain as a first constituent a procatalyst which is a titanium containing solid, usually a titanium-halide containing solid, and which often contains an electron donor. Suitable electron donors which may be 10 used in the production of the procatalyst are ethers, esters, ketones, phenols, amines, amides, imines, ni~riles, phosphines, arsines, stilbenes, phosphoramides or alcoholates. Among the preferred electron donors for use in the production o~ the procatalyst are phenols and e~ters, 15 particularly alkyl esters of aromatic carboxylic acids. The use of ethyl benzoate or diisobutyl phthalate is particularly preferred. The second catalyst component, termed a co catalyst, is an organoaluminum compound which is uncomplexed or is partly or totally complexed with the third 20 catalyst component which is conventionally termed a selectivity control agent. Typical selectivity control agents include esters (particularly aromatic esters), amines ~particularly hindered amines), phosphates, phosphites, hindered phenols, ~ilanes (particularly alkoxysilanes) and 25 aryloxysilanes and mixtures o~ two or more thereo~. Alkyl esters of aromatic carboxylic acids such as ~thyl p-ethylbenzoate, ethyl p-ethoxybenzoate and diisobutyl phthalaté and alkoxysilanes such as propyltximethoxysilane and diisobutyldimethoxysilane are preferred as the third 30 catalyst component.
Such stereoregular olefin polymerization catalysts are described in numerous patent~ and other references including US-A-4,72~,705. Although various chemical compounds are useful as constituents o~ the polymerization 35 catalyst, a typical high activity stereoregular ole~in polymerization catalyst contains as procatalyst a solid 2 ~ ". ~

comprising magnesium halide, a titanium halide and the electron donor. The halide moieties of such procatalysks are customarily chloride moieties. The cocatalyst is typically a trialkylaluminum compound ~uch as S triethylaluminum or triisobutylaluminum which i~ often at least partially complexed with the ~electivity control agent. Use of the catalysts of this type results in a stereoregular polymeric product when ~ ole~ins of three or more carbon atoms are polymerized. The catalysts are 10 recognised a~ high activity i~ they catalyze the production of polymers of desirable properties without the necessity of removing catalyst residues in a de-ashing step.
These catalysts are used in established processes to polymerize or copolymerize ~-olefins. The processes may 15 employ a liquid non-polymerizable diluent or alternatively may employ as liquid diluent a monomer o~ the polymerization. To obtain the compositions of the invention, however, it is desirable to utilize a gas phase process.
Various ga~ phase processes are known and conventional but one such process which can suitably be used to produce the impact polymer compositions of the invention is described in US-A-4,379,759 and involves a fluidized bed, gas phase reaction. A ga~ phase process is typically 25 operated by charging to a suitable reactor an amount of pre-formed polymer particles and a lesser amount of solid catalyst particles. The olefin(s) to be polymerized is (are) passed as a gas through the particle bed under conditions of temperature and pressure and at ~ rate 30 sufficient to initiate polymerization. Upon passing through the particle bed, the unreacted gas i5 withdrawn from the reactor and recycled together with make-up feed gas. As catalyst is lost through incorporation of minute amounts of catalyst within the polymer product, additional catalyst i5 35 provided to the reactor, often through the use o~ an inert transport gas such as nitrogen or argon. ~he reaction 2 ~ ~3,1~ , temperature is selected to be below the sintering temperature of the catalyst particles and is controlled by an external heat exchanger in a gas cycle loop. Reaction tempera~ures from 30~C to 120C may ~e used, wikh reaction 5 temperatures from 50'C to 90C being more commonly used.
The reaction pressure is generally up to 6.9 ~Pa (lO00 psi) although reaction pressures ~rom 0.69 to 2.76 ~Pa (100 to 400 psi) are preferred. The precise control of reaction conditions as well as the ad~ition o$ catalyst and feed gas lO and the recycle of unreacted monomer is within the skill of the art. An additional means of reaction and product control is achieved by the provision for the addition of molecular hydrogen to the reactor and ~hus the reaction system. The addition of molecular hydrogen serves to 15 control the molecular weight of the product, most likely by serving as a chain tran~fer agent. The use of molecular hydrogen to control the molecular weight of the polymer is also within the skill of the art.
The desired polymeric products are obtained as 20 particulatP- matter formed by growth o~ polymer product on the polymer particles provided to the fluidized bed or as particles formed in the reactor. The polymer particles are removed from the reactor at a rate which is substantially equival~nt to the rate o~ polymer production and the 25 particles are passed to a subsequent reaction zone or are finished by conventional methods prior to use.
It is possible al~hough impractical to produce the polypropylene impact copolymers of the invention in a single reactor by con~rol of the feed gas and recycle o~ unreacted 30 monomer and polymeric product. However, it is more common to operate the gas phase proces~ for production o~ the compositions of the invention as a two-stage process wherein each stage operates in the gaseous phase in one or more separate reactors. In such a modification, the 35 homopolymeric portion o~ the impact copolymer is initially produced as described above in a suitable gas phase reactor ' ' which generally but not necessarily employs molecular hydrogen to co~trol the molecular weight of the product.
This initial homopolymer product containing active catalyst sites is then passed to a second gas phase reactor 5 containing a second fluidized bed. A portion of unreacted ~onomer from the first reaction stage may be passed to the second ~tage together with the monomers to be employed in the production o the copolymer pha~e. The production of the copolymer or rubber phase takes place i~ the second 10 reaction stage where it may also be de~irable to provide molecular hydrogen to control the mslecular weight o~ the copolymer phase. In the two-stage gas phase polymerization process, two or more gas phase homopolymer or copolymer reactors can be used in various sequential or parallel 15 arrangements by engineering procedures known in the art.
The homopolymer pha~e of the impact polymer compositions of the invention is predominantly but not necessarily entirely homopolymer. To obtain particular properties for polymers used in particular applications it 20 may be desirable to incorporate in the otherwise homopolymer phase of the impact copolymer compositions a small amount, e.g. up to 6% by weight, of a second ~-olefin such as ethylene, l-butene or even a higher ~-olefin of up to 6 carbon atoms. The incorporation of an optional small amount 25 of second ~-olefin is by conventional methods and serves to modify but not substantially alter the properties of the homopolymer phase. In the embodiments where a small amount of second ~-olefin is incorporated the product, although technically a copolymer, is ~till referred to as the 30 homopolymer phase. The optional second ~-olefin i8 preferably ethylene, preferably incorporated in an ~mount up to 4% by weight~ However, the homopolymer phases whi~h are substantially homopolymeric polypropylene, i.e. phases produced in the sub~tantial absence o~ second ~-ole~in, are 35 preferred.
The second phase or rubber phase i8 a terpolymer .~' .
.
.
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phase comprising moieties of ethylene, propylene and a second a-olefin o~ at least 4 carbon atoms. The ethylene moieties are present in a major amount with moieties o~ the ~ olefin of a~ leas~ 4 car~on atoms being present in lesser 5 amounts and ~oieties of propylene present in even smaller amounts. The ethylene content i8 ~omewhat cri~ical since impa~t polymer compositions having too low an ethylene conten~ in the rubber phase lack ~he needed degree of protection against stress whitening, and too high an 10 ethylene content in the rubber phase results in brittle failure. In the impact copolymers of the inv~ntion the ethylene content o~ the rubber phase i~ ~uitably from 70% to 95%, preferably 80~ to 90%, by mole based on total rubber phase. The ~-olefin of at least 4 carbon atoms is 15 illustrated by l-butene, 1-hexene, l-pentene and 4-methyl-1-p~ntene. The preferred -olefin of at least 4 carbon atoms is l-butene. The proportion of ~-olefin of at least 4 carbon atoms which is present in the rubber phase is suitably from 2% to 29%, preferably 5~ to 20%, by mole based 20 on total rubber phase. The third component of the rubber phase is propylene which is suitably present in an amsunt from 0.7% to 15%, preferably 2% to 10%, by mole based on total rubber phase. The rub~er phase of the impact polymer compositions of the invention can cont~in small amounts of 25 some other polymerizable monomer including a second ~-olefin of at least ~ carbon atoms. In the preferred impact polymer compositions of the invention, however, the rubber phase ¢onsists essentially of moieties of ethylene, one ~-olefin of at least 4 carbon atoms, preferably 1-butene, and 30 propylene and the total proportion of such moieties is substantially 100%.
The production of the rubber phase of the impact polymer compositions is broadly within the skill of the art.
An initial homopolymer phase product containing active 35 polymerization sites is typically passed to a second gas phase reactor where the monomers required to produce the , ~ ,3~'~
-_ 9 _ rubber phase are present. Ethylene and an a-ole~in o~ at least 4 carbon atoms are introduced by conventional methods.
The product from production of th~ homopol~mer phase will often contain propylene monomer. Depending upon the 5 particular quantity of any propylene monomer present in the homopolymer phas~ product, ~he product is partially degassed be~ore in~roduction ~o the second reaction stage or is passed direc~ly into the second reactor with additional propylene monomer being ad~ed i~ necessary to provide the 10 desired proportion of propylene in the rubber phase product.
It may also be desirable on most occasions to provide molecular hydrogen to the second stage reactor to provide control of the molecular weight of the rubber phase.
The impact polymer compositions of the invention 15 therefore comprise polymers produced by a gas phase process having two phases. The homopolymer phase i8 predominantly propylene homopolymer, optionally with small amounts of other olefin present. The rubber phase is terpolymeric in character wherein ethylene units are present in major 20 proportions with a lesser proportion of units of ~-olefin of at least 4 carbon a~oms and an even smaller proportion of propylene units. The rubber phase of the polymers suitably constitutes from 10% to 60%, preferably 10% to 40%, by weight of the total pol~mer composition. Although the 25 compositions o~ the invention are literally at least terpolymers, they can appropriately be termed polypropylene impact copolymers because o~ the generally similar nature o~
the compositions of the invention to the more conventional propylene/ethy}ene impact copolymers.
The impact polymer compositions when produced by typical gas phase processes as described above will have melt flows, as determined by a conventional test procedure such as ASTM-1238, Condition L, of from 1 to 70. For some particular product applications it is desirable to have 35 impact copolymers of higher melt flow which is indicative of lower molecular weight. Increase of the melt flow of an ..

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olefin polymeric product is frequently accomplished by the use of molecul~r hydrogen as is also describ~d above.
However, an al~ernative method of lowering the molecular weight of the impact copolymer involves treatment at 5 elevated temperaturPs, e.g. above 180C, with peroxide, al50 termed ~Ivisbreaking~. In yeneral the use of visbreaking to lower molecular weight results in a lowering of resistance to stress whitening. When the impact polymer compositions of this invention are subjected to peroxide treatment, 10 however, the resistancs of the resulting products to stress whitening is comparable to that o~ non-visbroken conventional impact products. A second desirable property of the impact polymer compositions of the invention is that of gloss. With conventional propylene-ethylene impact 15 copolymers of high ethylene contents like the polymer~ o~
the invention, gloss is lost upon visbreaking. The good gloss of the compositions of the invention is, however, retained upon peroxide treatment to lower molecular wPight.
The compositions of the invention as well as the 20 peroxide-treated derivatives thereof are characterized by the good impact resistance and other good low temp~rature properties which are characteristic o~ conventional polypropylene impact copolymers. ~owever, in contrast with the conventional materials, the compositions of the 25 invention exhibit improved re istance to stress whitening and gloss which is of importance when the composition is employed to produce a final article where outward appearance is important. In addition to generally good tensile properties, the compositions of the inv~ntion may exhibit 30 strain hardening, i.e. the tensile strength at break is higher than the tensile strength at yield. This property is particularly desirable when thermoplastic-elastomeric low-to mid-range modulus polymers are desired ~or applications requiring good resilience, ductility and toughness as 35 exemplified by automotive bumpers and air dams.
The impact polymer compositions o~ the invention : : . . ' , ' ' I
' ' ., .

may suitably incorporate a variety of additives ~uch as ~tabilizers, antioxidants, fillers, colorants, nucleating agents and mold release agen~s which are conventionally employed in commercial polypropylene compositions. The 5 compositions o~ the invention are processed by conventional procedures used for thermoplastic materials such as lnjection molding, extrusion, thermofoxming and related processes. Among particular applications for the compositions are th production of molded and extruded lO automotive parts, ~mall appliance housings, film of improved clarity and gloss and stackable trays and luggage of improved toughness and reduced stress whitening.
The invention is further illus~rated by the followin~ Comparative Experiments (not of the invention) and 15 the ~ollowing Example which should not be regarded as limiting.
A number of samples of polypropylene impact copolymer, both within a~d without the scop~ of the invention, were produced by co~ventional two stage ga~ phase 20 processes and evaluated, primarily by conventional procedures. ~he stress whitening was evaluated by preparing injection molded disks, 6.4 cm (2.5 inches) in diameter and 0.32 ~m (0.125 inches) thick, from each ~ample. ~ ~tandard Gardner impact apparatus with the ring removed was used to 25 drop a weight upon an impactor, which contacts each disk, from a determined height and measuring the diameter of the whitened spot on the opposite side o~ the disk. All ~uch determinations were made 24 hours after molding. A 9.91 kg (2 lb) weight was used from heights of 12.3, 25.4 and 37.7 30 cm (5, lO and 15 inches) to obtain impacts of 11.52, 23.04 and 34.56 kg-cm (10 in-lb, 20 in-lb and 30 in-lb) respectively. The value reported was an average of 3 determinations.
In certain Runs of the Example the initial impact 35 copolymer composition was visbroken by one of two procedures. In a first procedure, termed "1", a sample of :, '. ~ '' , .

2 ~

the polymer as powder is heated with 2,5-dimethyl-2,5-bistt-butylperoxy)hexane in one extrusion pa~s. In a s~cond procedure, termed "2", the polymer in the form of pellets from an extrusion i~ treated with the same peroxide durin~ a 5 ~econd extruder pass.
Comparative Experlment I
To serve as a control, property determinations were conducted on two more conventional polypropylene impact copol~mer products having a rubber phase which comprised 10 units derived from ethylene and propylene. No ~-olefin of at least 4 carbon atoms was used in preparing the rubber phase. The results of these determination~ are shown in Table I. Test specimens were prepared by injection molding with an Arburg reciprocating screw machine.
~E I
Control Run No. __ 1 2 M~lt Flow 3.5 4.0 Tensile Pn~x~ties, 0.846 mm~s ( 2 ~ mLn~
Yield, kPz (psi) 30795 (4467~28472 (4130) 20B~k, XPa (psi) 16656 (2416)19524 (2832) Elongation Yield 8.6 7.1 Q ~k 108 228 Izod, Notched, J/cm (~t-lb/in) 2523C 0.45 (0.8~) ~.80(1.5) 0C 0.26 (0.49) 0.39(0.73) -20C 0.20 (0.38) 0.36(0.67) G~x~r ~ct, kg-cm (in-Ib), 30C 115 (133) 122(140) Gloss, ~ 60 d~e an~le 29.4 47.5 Sb~s Whit~n~, dia, cm (~n) 11.52 k~-cm (10 inrlb) 0 (0) 1.12 (~.44) 23.04 kg-cm (20 in-Ib) 0.20 (0.08)1.55 (0.61) 34.52 k~-cm (30 m-lb) 0.20 (0.08)1.70 (0.67) C2 m H~K~lymer, ~wt 1.5 o 35~wt Copolymer ~ 25 1~.5 %wt Ethylene in Ccpolymer ~ 95 60 2 ~ 3~

. - 13 -Example Property determination~ were also made for a nu~er of composition~ wi~hin the scope of the invention, be~ore and after visbreaking. The results are show~ in Table~
5 V, wherein the results shown in each Table are for the ~me polymer before and a~ter visbreaking.
In each instance wh2re appl~cable, reactor powder was dry mixed with additives/ including lOOOppm IRGANOX
1010, lOOOppm of IRGAFOS ~ 168 and 800ppm of calcium 10 stearate. For visbroken compositions the peroxide, 2,5-dimekhyl-2,5-bis(t-butylperoxy~hexane, was added as a 50:50 blend with mineral oil. For formulations of the 5'A" type, the peroxide-oil was dry mixed with the polymer powder and additives. For "B" type formulations, khe peroxid~-oil was 15 mixed with pellets, the latter having been prepar~d from one powder-to-pellets extrusion pass.
All extrusions were conducted under nitrogen (bleed to hopper and throat) on a 3.2 cm (1~ in) Brabender extruder using a mixing screw and an 80 ~esh screen.
20 Extruder melt temperatures were maintained at about 240C.
Test specimens were made by i~jection molding with an Arburg reciprocating screw machine.

T~BLE II
RLn NO! 3 3A 3B
25 Visbn~æn No Yes-l Y~s-2 Mblt Flow l.9 4.9 4.9 Tensile Pn~ties, 0.846 mm/s (2 in/min) Yield, kPa (psi) 21034(3051) 18883(2739) 20123t2919) E~ak, kPa (p6i) 23474(3405) 17945(2603) 19~62(27943 % Elonqation Q Yield 12.5 9.23 9.63 Q k~k 431 426 432 Izod, Nb~ , J/cm (ft-lb/in) 3523C 7.58(14.2) 6.68(12.5)6.19(11.6) 0C 3.38(6.33) 1.03(1.93)1.04~1.94) -20C ~.72~1.35) 0.67(1.26)0.70(1.31) . .
`'" :' ` , 2 ~

Gardner Impact,k~-cm(in-lb) -30C245(~83)222(Z56)225(259) Gloss, @ 60 d~ree ~le ~3.2 38.0 36.0 11.52 k~-c~ (lO ~ Ib) 0.56(0.22)1.12(0.44)0.86(0.34) 23.04 k~cm (20 mrib) 0~84(0.33)1.45(0.57)1.27(0.50) 34.52 kg-cm (30 m-lb~ 1.0g(0.43)1~47(0.62)1.~5(0.61) ~2 in Ho~cpo1ymer9 %Wt 1.1 %w~ Copolymer Phase 30 %wt Ethylene in Cbp~l~mer Phase 78 (86.9%m) %wt B~tylene in Copolymer Phase 17 (9.~m) ~wt Prqpylene In Ccpolymer ~hase 5 (3.7~m) ~ III
C~ntr~l Run No. 4 _ 4A 4B
15 VisbrDken No Yes-l Yes-2 Melt Flow 2.2 5.2 5.0 Iensil~ Properties, 0.846 mm/s (2 in/min) Yield, kPa (psi) 22109(3207) 20013(2903) 20544~2980) Break, kPa (psi) 2378~(3450) 19041(2762) 19082(2768) % Elonga~ion Yield 11.7 10.3 10.0 Q Break 431 425 414 Iæod, Notched J/cm (ft-Ib/Ln~
23~C 6.94(13.0)1.54(2.89~1.55(2.90) O~C 0.93(1.75)0.82(1.53)~.85(1.60) -20~C 0.57~1.07)0.55(1.03~0.58(1.0R) Gardner Impact,cm,kg(inrIb)-30~C 236(272)207(239) 214(247) Glo~s, Q 60 degree angl~ 42.2 42.9 42.9 Stress ~hitening, dia, cm (ln~
11.52 kg-cm(10 in-Ib) 0.66(0.26)1.14(0.45)1.02(0.40) 23.04 kg-cm(20 in-Ib) 0.94(~.37)1.50(0.59)1.52(0~60~
34.52 kg-cm(30 m -Ib) 1.17(0.46)1.70(0.67)1.65(0.65) G2 in Homopolymer, %wt 1.0 %wt Copolymer Phase 24 %wt EthylenR in Ccpolymer Phase 73 (84.2%m) 2 ~

- %wt Butylene in Ccpolymer Phase 26 (15.0~m~
%wt Prcpylene in Copolymer Phase 1 (0.8%m) l~E Iy C~ntr~l ~un No. 5 5~ 5B
5 Visbrcken No Yes-l Yes-2 ~el~ Plow 1.8 5.0 5~3 T~nsile Properties, 0.846 mm/s (2in/min) Yield, kPa (p6i)20702 (3003) 19103 (2771) 18641 (2704) ~0Break, kPa (p6i) 23150(3358) 18634(2703) 18117(2628) % Elongation Yield 12.9 10.2 9.89 ~ Break 431 ~27 431 Izod, Notched, J/cm (Pt-Ib/in) 1523C 7.B0(14.6) 7.00(13.1) 6.73(12.6) 0C 1.26(2.~6) 1.~5(1.97) 1.~1(2.08) -20~ 0.70(1.31) 0.76(1~42) 0.70(1.31) I~pact,kg-cm(in-lb),; 30C 254(2~3) 225(259) 215(248) Gloss, ~ 60 de~r~e an~le 42.4 40.0 39.8 20 stress Whitening, dia, cm (in) 11.52 kg-cm (10 in lb) 0.61(0.24)1.19(0.47)1.22(0.48) 23~04 k~-cm (20 in-lb)0~94(0~37) Lo47(~)~58) 1.5~)(0.593 34~52 k~ (30 u~ 14(0~45) 1~70(0~67~ 1~68(0~66) C2 in Homopolymer, %wt1~2 %wt Ccpolymer Phase 28 %wt ~thylene in CGpolymer ~hass 78 (86.6%m) %wt Butylene ln Copolymer Ehase 15 (8.3%m) %wt Propylene in Copolymer Ehase 7 (~ m) I~BIE V
30 C~ntr~l Run No, 6 _6~ 6B _ Visbrcken No Yes-l Yes-2 M~lt Flow 1.8 5.3 5.~

.:

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qensile Prqperties 0.846 mm/s) (2in/mm) Yield,kPa (psi) 21413 (3106) 20475 (2970) 19303 ~2800) Break,kPa (psi) 23550(3416) 19372(2810) 1884~3(2734) 5 % Elongation, ~ Yield 11.7 g.56 9.82 @ ~reak 431 421 431 Izod, Notched, J/cm (ft-Ib/in) 23 C 7.53 (14-1) 6.46(12-1) 5.28 (9.29) ~ -~ 1.05(1.g7) 1.03(1.9~) 1.0~ 7) -20C 0,70(1.32) 0.70(1.31) ~.73(1.37) Gardner Impac~,kg-cm(in-lb)l-30C 246t283) 224(258) 217~250) Gl06s, @ 60 degree angle 4~.3 40.2 42.3 Stress Whitening, dia, cm (in) 15 11.52 kg-cm(10 Ln-Ib) 0.76(0.30) 1.17(0.46) 1.27(0.50) 23.04 kg-cm(20 ~Ib) 1.09 (0.43) 1.52 (~.60) 1.55 (0.61) 34.52 k~-cm(30 inrlb) 1.27(0.50) 1.73(0.6~) 1.75~0.69) C2 In Homcpolymer, ~wt1.1 %wt Ccp~lymer ~ 26 20 %wt Ethylene m Ccpolymer Ehase 68 (80.3%m) %wt Butylene in Copolymer ~2 29 (17.3%m) %wt ~x~ylene in G~lymer ~ 3 (2.4%m) Comparative Example II
Proper~y determinations were made of a polymer 25 oomposition which was not within the ~cope of the present invention because of the absence of 1-butene moieties in the rubber phase. The results are shown in Table VI ~or this composition before and after vi~breaking.

30 Contr31 Run No. ~ _ 7A ~ 7B
Visbn~n No Yes-l Yes-2 M~lt Flow 1.9 5.3 5.5 Tensile Pn~x~ties, 0.846 nm/s (2in-min) Yield, kPa ~psi) 23964(3476) 22385(3247) 22123(3209) ~k, kPa (p6i) 19407(2815) 17aO0(2582) 17600(2553) .. ~, . . - , , .

,, . , ' ,.
: . " '' ~ : ' '' ,.

% ~longation ~ Yield 11.5 8.74 8.70 @ Braak 332 304 338 Izod, Nk~ gd, J/cm (ft~Ib/in) 23C 3.52(~.~0~0.84(1.57)0.81(1.52) 0C 0.52(0.97)0.~7(0.88~0.49(0.92) -20C 0.35(0.66~0.38(0.72)0.39(0.73) G~ux~er I~pact,kg-cm(in-Ib)~-30C 161(186)~22(141)116(134~
Gloss, ~ 60 dagree angle~3.0 34.8 34.1 10 stress ~, dia, cm (Jn~
11.52 kg-cm(10 in-lb) 0.51(0.20)1.09(0.43)1.~(0.45) 23.04 k~-cm(20 in-Ib) 0.81(~.32)1.45(0.57)1.55(0.61) 34.52 kg-cm(30 in-lb) 1.01(0.40)1.60tO.63)1.65(0.65) C2 in Homcpolymer, %wt. 1.1 ~wt Copolymer Fhase 26 ~wt Ethylene in Copolymer Ehase 78 %ht Prcpylene in Co~olymer ~hase 2 , ~ , ,

Claims (11)

The embodiments of the invention, in which an exclusive privilege or property is claimed, are defined as follows:

1. An impact polymer composition comprising a) a homopolymer phase of at least predominately homopolymeric propylene polymer and b) a rubber phase containing, in descending order of proportion, ethylene units, units of an .alpha.-olefin of at least 4 carbon atoms and propylene units.

2. A composition according to claim 1 wherein the propylene polymer of the homopolymer phase contains up to 6%
by weight of an .alpha.-olefin of up to 6 carbon atoms other than propylene.

3. A composition according to claim 2 wherein any second .alpha.-olefin present in the homopolymer phase is ethylene.

4. A composition according to claim 1 wherein the rubber phase contains from 70 to 95% by mole of ethylene units based on total rubber phase.

5. A composition according to claim 4 wherein the rubber phase contains from 80 to 90% by mole of ethylene units based on total rubber phase.

6. A composition according to claim 1, 2 or 3 wherein the rubber phase contains 2 to 29% by mole of units of an .alpha.-olefin of at least 4 carbon atoms based on total rubber phase.

7. A composition according to claim 1 wherein the rubber phase contains from 0.7 to 10% by mole of propylene units based on total rubber phase.

8. A composition according to claim 7 wherein the rubber phase contains from 2 to 10% by mole of propylene units based on total rubber phase.

9. A composition according to claim 1 wherein the .alpha.-olefin of at least 4 carbon atoms of the rubber phase is 1-butene.

10. A composition according to claim 9 wherein the rubber phase contains from 5 to 20% by mole of 1-butene units based on total rubber phase.

11. Shaped articles of a composition as claimed in claim 1, 2 or 3.